Below are games that can be built by 9 – 13 year olds. Arranged in order of increasing complexity.
Extremely simple game. Move with arrow keys, catch the gifts while avoiding bugs and falling baseballs (code here).
Highly simple game with a hidden maze. Move with arrow keys, you’ll go back when you hit a wall but pen shows you your last trail (code here).
Game based on Pong, left/right arrow keys to move paddles (code here).
Simple platformer, arrow keys to move and space to use solar-powered jetpack. Collect falling sun-rays to gain score and power the jetpack (code here).
More complex space-shooter. The ship follows the mouse, use arrow keys and space to shoot in space battles. Buy upgrades at the store (code here).